1. Field of the Invention
The present invention relates generally to transmission and reception of information in a broadcasting/communication system, and more particularly, to a method and apparatus for controlling a code rate according to transmission and reception of signaling information in a broadcasting/communication system.
2. Description of the Related Art
A broadcasting/communication system may experience poor link performance due to noise, a fading phenomenon, and Inter-Symbol Interference (ISI). Thus, to implement high-speed digital broadcasting/communication systems, which require high data throughput and reliability, development of a technique for overcoming noise, fading, and ISI is essential. To address these issues, research is currently being conducted on an error-correcting code, e.g., a Low-Density Parity Check (LDPC) code, for improving the reliability of broadcasting/communication by efficiently restoring distortion of information to an original state.
More specifically, an LDPC encoder receives LDPC information bits (or an LDPC information word or an LDPC uncoded block) having Kldpc bits to generate LDPC coded bits (or an LDPC code word, an LDPC codeword, or an LDPC coded block) having Nldpc bits. If the length of LDPC information bits input to the LDPC encoder, Kldpc, is shorter than the length of an input information bits (or input information word) to be encoded, Ksig, then a transmission end performs encoding after a shortening process. If the number of parity bits used by the transmission end, i.e., a parity bit length, Ntx_parity, is shorter than the length of parity bits output from the encoder, (Nparity=Nldpc−Kldpc), the transmission end punctures the parity bits output from the encoder by (Nparity−Ntx_parity).
If the shortening bit length increases, a code rate decreases, such that Bit Error Rate (BER)/Frame Error Rate (FER) performance may be improved in comparison to a code before shortening. However, if the puncturing bit length increases, a code rate also increases, such that the BER/FER performance may be degraded in comparison to a code before puncturing. Therefore, to maintain similar performance regardless of the length of an information word for system stability, a technique for selecting the appropriate number of puncturing bits according to the length of an information word is required.